The global Muslim population stands at 1.57 billion, meaning that nearly 1 in 4 people in the world practice Islam, according to a report billed as the most comprehensive of its kind.

The Pew Forum on Religion and Public Life report provides a precise number for a population whose size has long has been subject to guesswork, with estimates ranging anywhere from 1 billion to 1.8 billion.

The project, three years in the making, also presents a portrait of the Muslim world that might surprise some. For instance, Germany has more Muslims than Lebanon, China has more Muslims than Syria, Russia has more Muslims than Jordan and Libya combined, and Ethiopia has nearly as many Muslims as Afghanistan.

"This whole idea that Muslims are Arabs and Arabs are Muslims is really just obliterated by this report," said Amaney Jamal, an assistant professor of politics at Princeton University who reviewed an advance copy.

Christianity boasts 2.2 billion followers
Pew officials call the report the most thorough on the size and distribution of adherents of the world's second largest religion behind Christianity, which has an estimated 2.1 billion to 2.2 billion followers.

The arduous task of determining the Muslim populations in 232 countries and territories involved analyzing census reports, demographic studies and general population surveys, the report says. In cases where the data was a few years old, researchers projected 2009 numbers.

The report also sought to pinpoint the world's Sunni-Shiite breakdown, but difficulties arose because so few countries track sectarian affiliation, said Brian Grim, the project's senior researcher.

As a result, the Shiite numbers are not as precise; the report estimates that Shiites represent between 10 and 13 percent of the Muslim population, in line with or slightly lower than other studies. As much as 80 percent of the world's Shiite population lives in four countries: Iran, Pakistan, India and Iraq.

The report provides further evidence that while the heart of Islam might beat in the Middle East, its greatest numbers lie in Asia: More than 60 percent of the world's Muslims live in Asia.

About 20 percent live in the Middle East and North Africa, 15 percent live in Sub-Saharan Africa, 2.4 percent are in Europe and 0.3 percent are in the Americas. While the Middle East and North Africa have fewer Muslims overall than Asia, the region easily claims the most Muslim-majority countries.

While those population trends are well established, the large numbers of Muslims who live as minorities in countries aren't as scrutinized. The report identified about 317 million Muslims — or one-fifth of the world's Muslim population — living in countries where Islam is not the majority religion.

Volatile mix of religion, class and politicsIn several of these countries — from India to Nigeria and China to France — divisions featuring a volatile mix of religion, class and politics have contributed to tension and bloodshed among groups.

The immense size of majority-Hindu India is underscored by the fact that it boasts the third-largest Muslim population of any nation — yet Muslims account for just 13 percent of India's population.

"Most people think of the Muslim world being Muslims living mostly in Muslim-majority countries," Grim said. "But with India ... that sort of turns that on its head a bit."

Among the report's other highlights:

Two-thirds of all Muslims live in 10 countries. Six are in Asia (Indonesia, Pakistan, India, Bangladesh, Iran and Turkey), three are in North Africa (Egypt, Algeria and Morocco) and one is in sub-Saharan Africa (Nigeria).

Indonesia, which has a tradition of a more tolerant Islam, has the world's largest Muslim population (203 million, or 13 percent of the world's total). Religious extremists have been involved in several high-profile bombings there in recent years.

In China, the highest concentrations of Muslims were in western provinces. The country experienced its worst outbreak of ethnic violence in decades when rioting broke out this summer between minority Muslim Uighurs and majority Han Chinese.

Europe is home to about 38 million Muslims, or about five percent of its population. Germany appears to have more than 4 million Muslims — almost as many as North and South America combined. In France, where tensions have run high over an influx of Muslim immigrant laborers, the overall numbers were lower but a larger percentage of the population is Muslim.

Of roughly 4.6 million Muslims in the Americas, more than half live in the United States although they only make up 0.8 percent of the population there. About 700,000 people in Canada are Muslim, or about 2 percent of the total population.

A future Pew Forum project, scheduled to be released in 2010, will build on the report's data to estimate growth rates among Muslim populations and project future trends.

A similar study on global Christianity is planned to begin next year.

Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Muslim devotees leave the Jama Masjid mosque after evening prayers in New Delhi, India, Sunday, Sept. 20. Eid al-Fitr, a Muslim feast marking the end of the fasting month of Ramadan will be celebrated Monday across most parts of India.
(Gurinder Osan / AP)
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A woman sits between carriages as the train travels to Mymensing from Dhaka, Bangladesh on Sunday. Millions of Dhaka residents are travelling home from the capital city to celebrate the Eid al-Fitr holiday.
(Andrew Biraj / Reuters)
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A Pakistani beautician applies traditional henna designs to the hands of a customer ahead of the festival in Karachi on Sunday. Many Muslim women decorate their hands for Eid al-Fitr.
(Asif Hassan / AFP - Getty Images)
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Hundreds of thousands of Muslims perform the early morning Eid al-Fitr prayer at the Masjed Al-Haram grand mosque in the Saudi holy city of Mecca on Sunday. Islam's holiest shrine in Mecca will be the scene of the hajj pilgrimage in two months.
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Muslims, displaced by Indonesia's "mud volcano" (seen in the background), take part in a special morning Eid-al-Fitr prayer in front of the mud lake in Surabaya in East Java on Sunday. The "mud volcano," which erupted three years ago, has buried 12 villages, killed 13 people, displaced more than 42,000 residents and wiped out 1,977 acres of densely populated farming and industrial land. An Australian expert warned last June that it could keep spewing mud for the next 30 years.
(Mochammad Risyal Hidayat / AFP - Getty Images)
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A Palestinian Muslim woman, her hands seen on right, uses her mobile phone to take a picture of her husband and son in front of the Dome of Rock Mosque in the Al Aqsa Mosque Compound in Jerusalem's Old City, Sunday.
(Muhammed Muheisen / AP)
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